My Favorite Summer Weather Map Layers:

• StormNet Lightning Risk
• Current Lightning Strikes and 1-Hour Risk
• Current Radar
• Forecast Radar
• Forecast Total Precipitation
• Current Air Quality
• Smoke Surface Forecast (ground level)
• Smoke Sky Forecast (average smoke ground level to upper atmosphere)
• Forecast Air Quality (low-res 3-5 day smoke outlook)

5-Day Big Picture Overview:

It will be another hot week across the Interior West, but an active monsoon will continue to fuel daily rounds of thunderstorms across the Southwest and Central Rockies, with Colorado and Northern New Mexico favored for the heaviest rainfall.

A cooler airmass will remain over the PNW Coast and Western BC in response to a large trough off the West Coast, while a Pacific disturbance will also bring more showers to the Olympic Peninsula, Western BC, and Northern WA Cascades early in the week. 

COLORADO

Mon – Thunderstorms will develop over the higher peaks by midday, with thunderstorm coverage increasing statewide through the afternoon and evening hours in response to a shortwave moving through. Storms will track from WSW to ESE at 10-15 mph and will be capable of producing locally heavy rain. 

Tue – Another active day is expected with storms developing by noon over the higher peaks, followed by increasing coverage throughout the state during the afternoon hours. Storms will move from West to East at 15-20 mph, but stronger storms will be capable of producing heavy rain, especially across the Front Range Mountains and I-25 urban corridor. 

Wed – This will be another active day with scattered to widespread afternoon thunderstorms expected throughout the state. Storm motions will generally be W to E at 10-20 mph, with stronger storms producing heavy rain, especially around the Front Range. There is also a risk of large hail (1+ inch diameter) with storms east of the Divide.

Thu-Fri – Moisture levels will begin to decrease, so conditions will be less active compared to earlier in the week. However, isolated to scattered afternoon thunderstorms can still be expected throughout the state, with the Front Range and eastern mountains likely being favored a bit more compared to areas west of the Divide.

Our PEAKS Model favors the Front Range and Palmer Divide for the heaviest rain totals through Friday, with more modest (but still meaningful) amounts west of the Divide. Isolated higher totals are possible in areas where stronger thunderstorms develop.

UTAH

Mon – Scattered afternoon thunderstorms can be expected across most of the state, though the southwest Corner (Zion to St. George) and northernmost areas (Ogden to Logan) are less likely to see storms than other areas. 

Storm motions will be SW to NE at 10-15 mph across Southern/Central Utah and 15-25 mph across Northern Utah. The flash flooding risk is not as significant compared to last week, but is still very much a possibility in Southern Utah canyon country in the vicinity of stronger thunderstorm cells.

Tue – Thunderstorm coverage will be more isolated than what we've seen lately, with the highest lightning probabilities expected over the Uintas in Northern Utah and over the Grand Staircase-Escalante region in Southern Utah. There is still enough moisture to support a flash flooding threat with any stronger thunderstorms that develop.

Wed – An uptick in thunderstorm coverage is expected statewide as a shortwave trough moves through, although areas along and east of I-15 look to be most favored.

Stronger storms will be capable of producing locally heavy rain, though storm motions will be faster compared to what we saw last week, so the flash flooding threat will be more isolated, but still very much a concern in slot canyons, dry washes, etc.

Thu-Fri – Thunderstorm chances will be on the decline as drier air moves into Utah from the west. Areas west of I-15 may see little to no thunderstorm activity, while areas east of I-15 will hang onto isolated afternoon thunderstorm chances.

Here is our PEAKS Model total precipitation projection through Friday, which highlights the higher elevations as having the best chances to receive meaningful rain. Isolated higher amounts are possible in areas where stronger thunderstorms develop.

SOUTHWEST

Mon – Scattered terrain-driven thunderstorms will develop by midday across both AZ and NM and will continue through the afternoon, with stronger storms producing locally heavy rain. 

Tue – Similar conditions can be expected, though StormNet is picking up on a slight risk of morning thunderstorms across the Southeast Arizona Mountains. Scattered afternoon terrain-driven thunderstorms will develop once again, while the lower elevation deserts will see hot and dry conditions. 

Wed – More of the same with scattered to widespread terrain-driven thunderstorms, with stronger storms producing locally heavy rain. 

Thu-Fri – Drier air begins to push into Arizona, resulting in a downward trend in thunderstorm coverage, though isolated afternoon thunderstorms will remain possible over the Mogollon Rim and southeast mountains. New Mexico will see higher thunderstorm coverage as better moisture lingers further east.

Our PEAKS Model rain forecast through Friday favors the Mogollon Rim, San Francisco Mountains, Black Mountains, and Sangre de Cristo Mountains for the heaviest rainfall. Isolated higher amounts are possible in areas where strong thunderstorms develop. 

CALIFORNIA/SIERRA

A dry pattern can be expected throughout the week, with mild temperatures (near to slightly below average) early in the week giving way to above-average heat by late in the week. Local pockets of wildfire smoke are possible at times, especially in the vicinity of the Dove Fire burning near Sonora. Fire danger will gradually increase over time as the heat builds late this week.

PACIFIC NORTHWEST

Mon – Near-to-below-average temperatures are expected, with cloud cover and rain showers across the Olympic Peninsula, West Coast, and BC Coast Range as a leading-edge weaker disturbance moves through.

East of the Cascades, heavy wildfire smoke and poor air quality will continue to plague the region due to numerous large wildfires burning.

Tue – A Pacific trough will move across NW Washington and BC, producing more numerous and heavier rain showers across the Olympic Peninsula and Western BC, with the Northern WA Cascades also picking up lighter rain.

Total rainfall through Wednesday morning will be substantial across Western BC, with higher elevations picking up 1-2 inches. The west coast and higher elevations of the Olympic Peninsula will pick up 0.25 to 0.75 inches of rain, while the WA Cascades will see a trace to 0.25".

Areas east of the Cascades will not see any of this moisture, and if anything, the fire situation only looks to worsen due to strong winds as a cold front moves through the area.

Wed-Fri – A dry pattern can be expected with below-average temperatures west of the Cascade Crest and above-average temperatures east of the Cascade Crest on Wed-Thu, before warming up west of the Cascades on Fri.

The PNW will still remain under the influence of a trough-dominant pattern, which will favor gusty winds each day that will continue to fuel the wildfire risk. Also, smoke relief is not expected anytime soon across the Inland NW.

NORTHERN ROCKIES

Mon – Thunderstorms will favor Wyoming and, to a lesser extent, Southern Montana as a shortwave disturbance moves through. Wildfire smoke from Oregon will also result in reduced visibility and poor air quality across most of Idaho and Wyoming.

Tue – Isolated to scattered afternoon thunderstorms will favor Wyoming, Southwest Montana, and Eastern Idaho as monsoonal moisture remains in place. The remainder of Idaho and Montana will see drier conditions and continued heavy wildfire smoke.

Wed – A shortwave trough will move across the area, resulting in more widespread thunderstorm coverage across Wyoming, Southern Montana, and Eastern/Central Idaho, while Northern Idaho and NW Montana will remain in a dry and smoky pattern.

Thu-Fri – Moisture levels will be on the decrease, but we will still hang onto isolated afternoon thunderstorm chances across the same zones, including Wyoming, Southern Montana, and Eastern Idaho. There is no relief in sight as far as wildfire smoke goes, and if anything, smoke may expand into Wyoming at times.

BC INTERIOR & CANADIAN ROCKIES

Mon-Tue – Impacts from a Pacific trough will generally stay too far west and too far north. However, showers and thunderstorms will develop on Tuesday around Revelstoke, Golden, and from just north of Lake Louise along the Icefield Parkway up toward Jasper. 

Wildfire smoke will continue to be an issue from PNW and BC wildfires for the foreseeable future.

Wed-Fri – A drier pattern will take hold with cooler temperatures on Wednesday giving way to warmer temperatures on Thursday-Friday. Waves of wildfire smoke will also move through from the southwest.

Saturday (Aug 1) to Wednesday (Aug 5):

The monsoon will weaken substantially this weekend and into next week, in response to a strong (but moisture-starved) trough moving across the Northern Rockies and a shift in the subtropical high into Southern Nevada & California, which will largely cut off the flow of deep moisture.

A weak monsoonal flow will still persist over Southern Colorado, New Mexico, and Arizona, where afternoon terrain-driven thunderstorms will be common.

The heat will also build over Utah, Arizona, Nevada, and California in response to the high pressure ridge. California has escaped the worst of the wildfires so far this summer, but this building heat wave will steadily increase the fire danger.

Across the Northwest, temperatures will remain more moderate thanks to troughing off the West Coast, but continued gusty winds will not help with the ongoing wildfire situation. Similar to this week, Pacific disturbances could bring rain to the Olympic Peninsula and BC Coast Range from time to time. 

Thanks so much for reading! Next update on Wednesday (July 29).

Alan Smith